To date, normal saline water and liquid medicine and the like that are stored in containers such as vials or ampoules are suctioned using a syringe with a cannula attached to the tip, and this liquid medicine and the like is supplied to the patient through filling a prescribed area of a transfusion line connected to the patients body. The tip of this cannula comprises a narrow cylindrical needle, and there is an opening for injection and extraction of liquid medicine and the like formed in the tip of this cylindrical needle. Of the types of cannulae, there are those that are formed out of resin material to enable expanding shape selection width and to ensure safety. Furthermore, there are those where the opening is not prepared in the tip of the needle but in the side area of the tip of the needle (for example Patent reference 1: Published unexamined patent application 2002-17856).
In the case that this type of cannula is cast using injection moulding equipment prepared with a casting mould, a core area that forms the cast open area is placed between surfaces of the groove for casting and in addition, opening forming pins that correspond to the opening of the cannula in the mould body extend towards the core area from both sides and the tip areas contact the core area and in this state, casting material is injected into the casting open area through the injection opening of the mould body. Furthermore, in the case that an opening is not formed on both sides, but only one side of the tip, a pin for preventing inclination due to injection pressure of casting material contacts the tip area of the core on the surface opposite the surface where the opening forming pin in the core area contacts and injection moulding is performed with this condition. In addition, processing treatment to fill the hole cast by the pin for preventing inclination is performed after casting.
However, of the aforementioned conventional cannulae manufactured using a resin, when producing a cannula with an opening formed on one side of the tip area, there was the problem that manufacturing processes increased due to the necessity of processing treatment to close the hole formed by the pin for preventing inclination and in addition there was the possibility that the surface of the cannula would be rough after closing the hole, lowering the quality of the cannula.
Taking these circumstances into consideration, the purpose of the present invention is to provide a casting mould and casting method for cannulae enabling a reduction of manufacturing processes and increasing quality by enabling the forming of a smooth surface.